Spinal instability is often attributed to undesirable excessive motion between vertebrae which can cause significant pain and morbidity. The instability may result from a number of causes, including abnormalities of the vertebrae, the intervertebral discs, the facet joints, or connective tissue around the spine. These abnormalities may arise from diseases, disorders or defects of the spine from trauma or bone degradation, such as osteoarthritis, or degenerative disc disease. When the spine becomes unstable, the vertebral column becomes misaligned and may allow micromotion between adjacent vertebrae. Vertebral misalignment and micromotion may result in wear to the vertebral bone surfaces and ultimately generate severe pain. These conditions are often chronic and create progressive problems for the sufferer.
Known treatments for spinal instability can include long-term medical management or surgery. Medical management is generally directed at controlling the symptoms, such as pain reduction, rather than correcting the underlying problem. For some patients, this may require chronic use of pain medications, which may alter the patient's mental state or cause other negative side effects. Surgical treatment typically includes decompression procedures to restore normal disc height, realign the column, and alleviate the pain.
Recently, a variety of interspinous vertebral stabilization devices have become available and have achieved clinical success. These devices are typically implanted between the spinous processes of two or more adjacent vertebrae. These devices may be motion-preserving, and provide various degrees of controlled movement of the spine while supporting the adjacent vertebrae. Other devices may be fusion-promoting. For instance, the fusion-promoting devices can be secured between adjacent spinous processes using a number of different mechanisms. For example, such devices can include sharp barbs or other surface projections that engage the bony surface of a spinous process. In addition, flexible ligaments or sutures can be placed around the implants to secure them to adjacent bone. In some cases, the devices may be rigidly attached to the spinous processes using a bone screw or other suitable bone anchor to prevent the interspinous stabilization device from migrating or slipping out of position. When the device is fastened to the spinous processes in this rigid manner, the device allows for fusion at this segment of the spine.
Some of these interspinous/interlaminar stabilization devices, such as those described in U.S. Pat. Nos. 5,645,599 and 7,922,750, for example, include an interspinous/interlaminar body portion having a U-shaped midsection for insertion into the interspinous/interlaminar space between adjacent vertebrae. In these and other interspinous/interlaminar stabilization devices, pairs of wings or brackets extending from the body portion and extending upwardly and/or downwardly create receiving spaces or slots for seating spinous processes of the adjacent vertebrae to keep these devices in place. To facilitate implantation and secure attachment of the wings of the devices to the spinous processes, it may be desirable to bend or crimp the wings to either expand the receiving space to receive the spinous process, or secure the wings to the spinous process.
By stabilizing the spinous processes in this way, significant stress may be taken off the intervertebral discs to alleviate pain, prevent disease progression or to improve conditions such as spinal stenosis. In addition, vertebral motion may be controlled without severely altering the anatomy of the spine. Further, treatments involving these interspinous/interlaminar vertebral devices are less invasive, may be reversible, and cause a less drastic alteration in the patient's normal anatomy and spinal function. These procedures may be used at an earlier stage of disease progression and, in some situations, may halt, slow down or even reverse the disease progression.
However, the benefits and advantages of these devices can only be realized if the interspinous interlaminar stabilization devices are properly implanted within the patient. This requires the surgeon to assess the proper size (e.g., height and depth) of the interspinous/interlaminar space so that the appropriately sized device is selected and implanted. Additionally, adjustments to the wings of these devices may be needed prior to implanting in order to open up the receiving space and accommodate the anatomy of the spinous process. Once implanted, adjustments may also need to be made to the wings to crimp them onto the spinous process.
It is desirable to therefore provide instruments that are able to assist the surgeon to properly implant these types of interspinous/interlaminar stabilization devices. It is further desirable to provide disposable instruments that do not require resterilization for reuse, thereby reducing risk of infection as a result of reuse and costs associated with these procedures.